1. Field of the Invention
The present invention relates to a signal recording device and signal recording method for recording video/audio data on a recording medium. More specifically, the present invention relates to a device and method for selecting an appropriate encoded signal from among the signals encoded at different compression ratios and recording the selected encoded signal on a recording medium.
2. Description of the Related Art
Examples of conventional devices for recording/reproducing video/audio signals include a DVD recorder, a hard disk recorder, etc., which perform MPEG (Motion Picture Experts Group) compression and encoding on video/audio signals and record the compressed and encoded signals on a recording medium.
Japanese Unexamined Patent Publication No. 9-284715 (Document 1) discloses an apparatus for encoding and recording/reproducing video data. In this apparatus, if the free space of a recording medium is insufficient for recording a video program, the compression ratio for compressively encoding the video signal is increased to reduce the size of the encoded data, whereby the entirety of the video program is recorded in the medium.
FIG. 26 is a block diagram showing a structure of a conventional recording/reproducing apparatus. This apparatus includes video signal input means 10, compressive encoding means 20, recording means 30, a recording medium 40, free space detection means 50, recording time designation means 60 and free space deficiency calculation means 70.
Now, consider a case where the recording/reproducing apparatus shown in FIG. 26 records a video program. In this apparatus, if the free space of a recording medium is insufficient, the compression ratio at which the compressive encoding means 20 compressively encodes a video signal is changed according to the deficiency of the free space which is calculated by the free space deficiency calculation means 70 based on the free space of the recording medium detected by the free space detection means 50 and the recording time designated by the recording time designation means 60, whereby the entirety of the video program is recorded.
The services of the BS and CS digital broadcast programs have already been started, and the services of digital terrestrial broadcasts have been started in the year-end season of 2003.
Now, consider the case of recording a video program received through a digital broadcast system. In the digital broadcast system, the video program is MPEG-compressed and encoded before it is broadcast.
Thus, in a conventional recording/reproduction apparatus, if the free space of a recording medium is insufficient, it is necessary to once decode a MPEG-compressed video program and then again compressively encode the decoded video program according to the deficiency of the free space.
FIG. 27 is a block diagram showing a structure of a conventional recording/reproduction apparatus wherein an MPEG-compressed encoded video program of a digital broadcast is recorded. This apparatus includes decoding means 80 in addition to the components of the recording/reproduction apparatus of FIG. 26. After the decoding means 80 has once decoded the video program of the digital broadcast, the compressive encoding means 20 changes the compression ratio used when the compressive encoding means 20 compressively encodes the video signal according to the deficiency of the free space calculated by the free space deficiency calculation means 70. That is, the free space deficiency calculation means 70 and the decoding means 80 are necessary for recording a video program of a digital broadcast in a recording medium whose free space is insufficient.